The mysterious inner workings of Chang Shan—a Chinese herbal medicine used for thousands of years to treat fevers associated with malaria—have been uncovered thanks to a high-resolution structure solved at The Scripps Research Institute (TSRI). Described in the journal Nature this week, the structure shows in atomic detail how a two-headed compound derived from the active ingredient in Chang Shan works. Scientists have known that this compound, called halofuginone (a derivative of the febrifugine), can suppress parts of the immune system—but nobody knew exactly how.